The field of the invention is telescopic sights for firearms. Such sights magnify the target and make it possible to identify and aim accurately at small targets even at long ranges and under poor light conditions.
Telescopic sights are precisely adjustable for alignment and zeroing. While some telescopic sights are adjusted by adjustments made in the mount, the typical scope contains a pair of very precise adjustments which move the reticle cell of the sight by means of a finely threaded internal stem which protrudes outwardly from the scope. External adjustment knobs are provided on many scopes however, such knobs are often inconvenient and lead to maladjustment because they may be inadvertently moved by contact with other objects. Therefore, many telescopic sights are provided with turret caps which cover the adjustment means. Commonly, the adjustment means consists of a slotted screw head which protrudes outwardly from the body of the sight and may be moved by a coin, screwdriver or other object which fits into the slot. A threaded cap covers the scope adjustment coin slot in order to prevent its unintentional movement.
For many uses, however, the external adjustment knob is desirable and facilitates the zeroing in of the scope because of its ease of use and because it may be readily turned by the fingers. Many times the sight is used under conditions where the use of the standard turret cap cover is unnecessary while at other times, the same sight would be used under conditions when the cover would be highly beneficial. For instance, the turret caps would be useful while the firearm is being transported but would be an inconvenience once the firearm was being used in the field or on a firing range. It has heretofor been impossible to provide an adjustment screw which is both easily adjusted in use and secure against misalignment during transit.